Norouzi S, Wagner T, MacDonald A, Bischoff J, Brasche J, Trojahn S, Spray J, Pereira R
The Lyell Centre, Heriot-Watt University, Edinburgh, UK.
British Geological Survey, The Lyell Centre, Edinburgh, UK.
Sci Rep. 2024 Feb 8;14(1):3270. doi: 10.1038/s41598-024-53362-z.
Dissolved organic matter (DOM) and its composition in aquatic ecosystems is a key indicator of ecosystem function and an important component of the global carbon cycle. Tropical rainforest headwaters play an important role in global carbon cycling. However, there is a large uncertainty on how DOM sources interact during mobilisation and the potential fate of associated carbon and nutrients. Using field techniques to measure dissolved organic carbon (DOC) concentration and composition, changes in DOM source from headwaters to larger downstream rivers were observed. This study shows that the hydrological connectivity, developed during the transition from dry to wet seasons, changes the DOM supply and transport across a tropical river catchment. The observed variability in the DOC-river discharge relationship provides further evidence of the changes in the DOM supply in a small headwater. This novel insight into the seasonal changes of the dynamics of DOM supply to the river helps understanding the mobilization of terrestrial DOM to tropical headwaters and its export from smaller to larger rivers. It also highlights the data gap in the study of smaller headwaters which may account for uncertainty in estimating the terrestrial carbon transported by inland waters.
溶解有机物（DOM）及其在水生生态系统中的组成是生态系统功能的关键指标，也是全球碳循环的重要组成部分。热带雨林源头在全球碳循环中发挥着重要作用。然而，关于DOM来源在迁移过程中如何相互作用以及相关碳和养分的潜在归宿，存在很大的不确定性。利用实地技术测量溶解有机碳（DOC）浓度和组成，观察到从源头到下游较大河流DOM来源的变化。本研究表明，在从旱季到雨季的过渡期间形成的水文连通性，改变了热带河流集水区内DOM的供应和运输。DOC与河流流量关系中观察到的变异性，进一步证明了小源头中DOM供应的变化。这种对河流DOM供应动态季节性变化的新见解，有助于理解陆地DOM向热带源头的迁移及其从小河流向大河流的输出。它还凸显了小源头研究中的数据缺口，这可能是估算内陆水体输送的陆地碳时存在不确定性的原因。
